Cyclodextrin-enhanced 1,4-dioxane treatment kinetics with TCE and 1,1,1-TCA using aqueous ozone

Enhanced reactivity of aqueous ozone (O-3) with hydroxypropyl-beta-cyclodextrin (HP beta CD) and its impact on relative reactivity of O-3 with contaminants were evaluated herein. Oxidation kinetics of 1,4-dioxane, trichloroethylene (TCE), and 1,1,1-trichloroethane (TCA) using O-3 in single and multiple contaminant systems, with and without HP beta CD, were quantified. 1,4-Dioxane decay rate constants for O-3 in the presence of HPOCD increased compared to those without HP beta CD. Density functional theory molecular modeling confirmed that formation of ternary complexes with HP beta CD, O-3, and contaminant increased reactivity by increasing reactant proximity and through additional reactivity within the HPPCD cavity. In the presence of chlorinated co-contaminants, the oxidation rate constant of 1,4-dioxane was enhanced. Use of HP8CD enabled O-3 reactivity within the HP8CD cavity and enhanced 1,4-dioxane treatment rates without inhibition in the presence of TCE, TCA, and radical scavengers including NaCI and bicarbonate. Micro-environmental chemistry within HPRCD inclusion cavities mediated contaminant oxidation reactions with increased reaction specificity. (C) 2018 Elsevier Ltd. All rights reserved.